Spin-State Tuning in PrFeO<sub>3-δ</sub> Perovskite for High-Temperature Oxygen Evolution Reaction
Jingrong Yu, Qingxue Liu, Shuo Wang, Shiming Zhou, Rongtan Li, Weicheng Feng, Yige Guo, Xiaomin Zhang, Rile Ge, Junhu Wang, Limin Liu, Shaowei Zhang, Geng Zou, Yuefeng Song, Guoxiong Wang, Xinhe Bao
Abstract
The electrocatalytic activity of perovskite oxides is fundamentally governed by their electronic structure. However, a deeper understanding of the relationship between the e g electron occupancy and high-temperature oxygen evolution reaction (OER) performance in solid oxide electrolysis cells (SOECs) remains underexplored. Here, A-site doped Pr 0.5 Ae 0.5 FeO 3−δ (Ae = Ca, Sr, Ba) are constructed with exceptional high-temperature OER performance, and Pr 0.5 Ba 0.5 FeO 3−δ achieves a current density of 3.33 A cm –2 at 2.0 V and 800 °C. X-ray absorption spectroscopy, 57 Fe Mössbauer spectroscopy, and magnetic susceptibility measurements reveal that alkaline earth metal doping induces a spin-state transition from high-spin Fe 3+ (t 2g 3 e g 2 ) to low-spin Fe 4+ (t 2g 4 e g 0 ), with reduced e g occupancy, thus accelerating the charge transfer and oxygen transport in the OER process. This work sheds light on the critical role of the B-site Fe electronic structure in high-temperature OER performance and provides guidance for the rational design of Fe-based perovskites as SOEC anode materials.